Field of the Invention
The invention relates to a suction head for a feeder of a sheet-fed rotary printing press and, more particularly, to such a suction head having a double sucker formed of two juxtaposed suction nozzles which are disposed in a line transversely to a sheet travel direction and are mutually connected by a tube extending transversely to the sheet.
Such a suction head has become known heretofore from U.S. Pat. No. 4,869,489. In the suction head, according to this patent, juxtaposed lift-type suckers, disposed transversely to sheet travel or feeding direction, are combined in pairs to form double suckers, one double sucker being disposed on each side of the suction head, so that at least two double suckers, usually, however, in conjunction with further suckers, comprise a suction head, which is of mirror-image symmetrical design with respect to a central longitudinal axis of the printing press. Furthermore, it has become known from the aforementioned patent to dispose the double sucker, in the form of a lift-type sucker with two suction nozzles, in a height-adjustable manner on a guide part, on which there is provided an axially displaceable, telescopically guided cylinder with a transverse tube attached thereto, the transverse tube connecting the two suction nozzles, so that both, together with the transverse tube and the cylinder, form a common suction chamber. A suction head with such double suckers is capable of processing all types of paper and cardboard at high conveying speeds without difficulty. Finally, it has become known from this patent to arrange the suction nozzles so that they are exchangeable.
The construction of the suction head and also of other heretoforeknown suction heads is based upon the maximum size or format of the sheet to be processed by a printing press. In the heretoforeknown constructions the suckers are disposed on both side of the central longitudinal axis of the printing press in mirror-image symmetrical positions with respect to the latter.